This invention relates generally to abrasive tools and more particularly to sanding blocks used to support and tension a continuous abrasive belt about the periphery of the tool. Sanding blocks using endless sandpaper belts are known. U.S. Pat. No. 2,414,036 (Gerhan) discloses a sandpaper block of two parts having ratchet teeth or double wedges to provide an elongation of the tool body and thus a tensioning of a continuous abrasive belt wrapped about the periphery of the two part block. U.S. Pat. No. 2,430,785 (Scattone) discloses an abrasive board for jewelers utilizing a handle connected to a working section about which a number of continuous abrasive belts are held. The belts are tensioned by a wedge driven into the board at the end opposite the handle. Successive layers of abrasive material are exposed by removing spent belts using rip strings. U.S. Pat. No. 2,493,852 (Bonkowski) shows a teardrop shaped sanding block for use with continuous sanding belts. It employs a string or thumbscrew mechanism to elongate the tool thereby tensioning and encircling abrasive belts. U.S. Pat. No. 2,761,257 (Mendelsohn) discloses a sanding block in which tension is imparted to an abrasive belt through a spring and guide arrangement contained within an opposed pair of sanding block halves. U.S. Pat. No. 3,063,208 (Bell et al.) discloses a sanding block comprised of three main body pieces with a diagonally oriented screw advance mechanism which elongates the tool to tension a continuous abrasive belt around the periphery of the tool. These disclosures contain the most pertinent art known to this applicant.